Testing machine



Feb. 21, 1928. I

D. J. MCADAM. JR

TESTING MACHINE Filed Feb. 4, 1921 2 Sheets-Sheet l Feb. 21, 1928. I 1,660,270

\ D. J. MOADAM, JR

TESTING MACHINE Filed Feb! 4. 1921 2 Sheets-Sheet 2 Patented Feb. 21,1928. x v

UNITED STATESPATENT OFFICE.

TESTING MACHINE COMPANY, OF IHILADELPHIA, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

TESTING MACHINE.

Application filed February 4, 1921. Serial No. 442,480.

This invention relates to that class of ma- Through a link 12 the pin 9 is connected chines particularly designed for subjecting to the lower end of an arm 13 whose upper a test specimen to alternating torsiona end is fixed to a short shaft 14 mounted in stresses and one object thereof is to provide an anti-friction bearing 15 preferably though 6 a relatively simple and substantial device'of not necessarily carried on the upper part 55 such design and construction as to permit of the frame 2, in line with a second short 7 of a highly accurate determination of the shaft 16 mounted in a similar anti-friction tr li d t h speci en. 7 bearing 17 The adjacent ends of said two It is further desired to provide a testing shafts 14 and 16 are suitably formed to pro-v machine of the above general type which vide or" have mounted on them chucks or 00 shall employ or utilize an oscillatory fly holders for a test'specimen sand the shaft Wheel as part of its stress applying means 16 has fixed to it a fly wheel 18. and shall include means adjustable to cause The outer or free end of the shaft 16 on said wheel to oscillate through any desired W i h h fly Wheel 18 is carried has mounted angjg on it a mirror 19 positioned to receive a beam 65 A th bj t. f my i ti i to m of light from a light tube 20 mounted on a vide a novel device for accurately measuring m mber "21 Which braces the frame 2 to the angle of oscillation of an oscillatory the base 1, and said tube consists of a closed member such as avfiy wheel forming part of Con ainer having within it a sourceof light 2" the stress applying mechanism of ,a testing such as an incandescent lamp 22. The tube 7 machine, together with novel means for .ada f rme in it a suitably placed, elongated j ti h angle t ill t vary th Stresses slit through which the light from said source li d t a t t Specimen may be. pro ected toward the mirror 19 in Th bj t d th advantageous end the form of a narrow beam and a double con- I attain as hereinafter set forth, reference VeX lens2 3 is suitably mounted on the frame 7 being had to the accompanying drawings, in 2 111 the line of the beam from the lighttub'e which, "20 so as toconcentrate the same upon the Fig. 1 1s an end elevation of a machine mirror. e v constructed in accordance with my inven- Smtably mounted adjacent the above de ti d scribed apparatus'and in the present in- Fig. 2 is a side elevation of the machin stance carried partly from a bar 24 projectshown in Fig. 1, with the scale and, hood g fr m the frame 2 and partly from the itt d vertical support 25, is a suit-able hood 26 in In the above drawings, 1 represents asuitthe form of a square prismatic or conical 35 bl b supporting Structure on hi h i structure having mounted Within it a scale mounted a frame 2 providing bearings for 27vupon-Which the mirror. 19 may reflect the a horizontal shaft made in two sections 3-4 beamof light from the light tube20.. e connected by aflexible coupling 5, the first Under conditions of operation the motor section either as in the present instance con- 6 turns the, shaft 34,in a typical caseat 40 stituting the armature shaft of a driving a speed of 1200 revolutions per minuteand motor 6 or being suitably coupled to some the resulting rotation of the crank disc 8 other source of power. The section 4 of said with its pin causes the arm 13 with the shaft shaft has fixed to it a relatively heavy fly 14 to be oscillated. If a test specimen a: be wheel-7 and acrank disc 8 and the latter connected between said shaft and the shaft 45 has mounted in it an adjustable crank pin 16, the inertia of the fly Wheel 18 causes al- 9,.carried upon a block slidably mounted in ternating torsional stresses to be applied to aradial slot 10 where it is adjustable radially said specimen, asthe two shafts 14 and 16 of the disk by means of asuitably mounted are alternately oscillated in opposite direcscrew 11, thus permitting the throw or ections. The maximum torsionalmoment thus 50 centricity of the pin 9 to vbe varied at will. produced is proportional to the moment of inertia of the fly wheel 18, to the maximum angular rotation of said wheel and to the square of the frequency of its oscillation.

The torsional moment T in absolute units may be calculated from the formula:

To obtain va formula for calculating the maximum stress in the specimen m, use must be made of aformula expressing the relation between the torsional moment and the maximum stress produced in a cylindrical specimen, as follows:

'rrsd in which S represents thestress in pounds per square inch and d represents the diam-, eter of the specimen in inches.

d (3), there is Combining formulas (2) an obtained 7 r19 7 4) ew g If the amplitudeof oscillation. of the fly wheel 18 or any equivalent structure whose mass is uniformly distributed about its axis of oscillation, is expressed in degrees with the designation 9, and the constants are combined, there is obtaineda formula:

' 1 0.0091619 SFW In a machine which I have successfully employed, the moment of inertia of the fly wheel was 142 pound-inches and the specimen operated on was 0.5 inches in'diameter.

For this machineand specimen therefore the constants when combinedgavethe formula:

(6) S='.O. OO2888R* 2 The accuracy of the stress measurements therefore depends on the measurement of the angle t and in the machine above described this angle was accurately measure d by noting the amount of movement of the beam of light reflected from the mirror 19vupon'th e scale 27 whichwastranslucent.

The light tube 20, the lens 23 and said I serving scale were so related that the image of the e narrow slit in the upper end of said light tube extended horizontally on said scale. Consequently when the fly wheel 18 was oscillated through an angle of 2 cf) the reflected beam of light oscillated through an angle of 4 4), thus producing a band of light upon the scale whose width depended on the distances of the tube 20, the lens 23 and the scale 27 from the mirror ;there being provided a Vertical slit inthe member 31 enclosing the large end of the hood for the purpose of ohthe light image formed on the screen 27.

With the above described arrangement'the scale 27 maybe placed at such a distance fromthe mirror 19that the annular measurement required may be made with a high degree of accuracy and in the machine operated by me one-fourth the width of the light band in centimeters'is a measure of the value of the angle (till degrees, the error in angular measurement and consequently the error in stress measurement'being not more than about one per cent. Any desired and suitable device may be employed for mamtaining constant the speed of the electric motor throughout the test. r By means ofthe above described machine a testspecimen of asuitable size, after being clamped in the chucks or holders provided on the adjacent ends of the'shaft sections 14 and 16, may have applied to it alternating torsional stresses until it fails and the amount of such stresses may be accurately determined by the scale measurement above described and the solution of the stress for mula above given I claim: 7

1, The combination in a'testing machine of two rotatably mounted members respectively engaging a test specimen; means for oscillating one of said members; and a'body having its mass uniformly disposed about its axis of oscillation, connected to the other member to oppose, by its inertia, oscillation of the first member, said means including a member having a fiy-wheel effect.

2.1 The combination in a testing machine of two vrotatably mounted members'respectively engaging a test specimen; means for oscillating one of saidmembers including an 'arm and link, the latter having an adjustablemounting'; and a flywheel connected to I the second member. 1 p a i (3. The combination in a testing machine of two aligned rotatable shafts; operating means connected to one of the shafts in cluding an arm and link; and a fly wheel connected to the other shaft. 7

. 4." The combination in a testing machine ,of two shafts rotatably mounted in'the same line'; an arm connected to one of .said'shafts; a ,fiy wheel connected to the other shaft;

and means for oscillating said armincluding a device for adjusting the angle of oscillation at will.

5. The combination in a testing machine of two members respectively engaging a test specimen; a radial adjustable crank connected to one of said members; a fly wheel connected to the other member to oppose alternating torsional force to oscillation of the test specimen; with means for rotating the crank to operate the member connected thereto.

6. The combination in a testing machine of two rotatably mounted members respectively engaging a test specimen; an arm connected to one of said members; a fly wheel connected to the other member; a motor driven crank; and a link connecting said crank with said arm. I

7. The combination in a testing machine of two rotatably mounted members respectively engaging a test specimen; an arm connected to one of said members; a fly wheel connected to the other member; a motor driven crank; a link connecting said crank with said arm; and means for adjusting at will the angle of oscillation of the arm.

8. The combination in a testing machine of two rotatably mounted member respectively engaging a test specimen; means for oscillating one of said members; a fly wheel connected to the second member; and means for measuring the angle of oscillation of the fly wheel.

9. The combination in a testing machine of two rotatably mounted members respectively engaging a test specimen; means for oscillating one of said members; a fly wheel connected to the second member; and means for measuring the angle of oscillation of the fly wheel, consisting of a source of light, a scale, and a mirror movable with the fly wheel for directing light from said source adjacent said scale.

10. In a testing machine, the combination with an oscillatory body, the mass of which is uniformly disposed about its axis of oscillation; of means adapted to connect a specimen with said body; means for oscillating said specimen about an axis concentric with that of said body; and means for indicating the angle of oscillation of said body.

11. In a'testing machine, the combination with a fly-wheel; of means adapted to operatively connect a test specimen to said flywheel; means for actuating said test specimen about an axis concentric with that of said fly-wheel, whereby the specimen may be stressed; and means for indicating the resulting movement of the test specimen.

12. In a testing machine, the combination with two rotatably mounted members adapted to engage a test specimen; of a flywheel connected to one of said members; means for oscillating the other of said members, so that said specimen may oscillate about an axis concentric with that of said fly-wheel; and a mirror movable with said fly wheel, whereby the angle of oscillation of said fly wheel may be ascertained.

13. In combination, a fiy-wheel; means adaptedto connect a specimen to said flywheel; means for oscillating said specimen about an axis concentric with that of said fly-wheel; means for measuring the angle of oscillation of said fly-wheel including a mirror movable with said specimen; and a lens and scale in operative relation to said mirror.

14. In combination, a supporting means for a test specimen; a fly-wheel operatively associated with said supporting means; means for oscillating said specimen; a source of light; a lens; a mirror movable with said fly-wheel for reflecting the light passing through said lens; a scale for re ceiving the reflected light; and a hood for enclosing said scale.

DUNLAP J. MoADAM, J12. 

